RegistryMBean.java

/*
 * Licensed to the Apache Software Foundation (ASF) under one or more
 * contributor license agreements.  See the NOTICE file distributed with
 * this work for additional information regarding copyright ownership.
 * The ASF licenses this file to You under the Apache License, Version 2.0
 * (the "License"); you may not use this file except in compliance with
 * the License.  You may obtain a copy of the License at
 * 
 *      http://www.apache.org/licenses/LICENSE-2.0
 * 
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */


package org.apache.tomcat.util.modeler;


import java.util.List;

/**
 * Interface for modeler MBeans.
 * 
 * This is the main entry point into modeler. It provides methods to create
 * and manipulate model mbeans and simplify their use.
 *
 * Starting with version 1.1, this is no longer a singleton and the static
 * methods are strongly deprecated. In a container environment we can expect
 * different applications to use different registries.
 * 
 * @author Craig R. McClanahan
 * @author Costin Manolache
 * 
 * @since 1.1
 */
public interface RegistryMBean {

    /** 
     * Load an extended mlet file. The source can be an URL, File or
     * InputStream. 
     * 
     * All mbeans will be instantiated, registered and the attributes will be 
     * set. The result is a list of ObjectNames.
     *
     * @param source InputStream or URL of the file
     * @param cl ClassLoader to be used to load the mbeans, or null to use the
     *        default JMX mechanism ( i.e. all registered loaders )
     * @return List of ObjectName for the loaded mbeans
     * @throws Exception
     * 
     * @since 1.1
     */ 
    public List loadMBeans( Object source, ClassLoader cl ) throws Exception;

    /** Invoke an operation on a set of mbeans. 
     * 
     * @param mbeans List of ObjectNames
     * @param operation Operation to perform. Typically "init" "start" "stop" or "destroy"
     * @param failFirst Behavior in case of exceptions - if false we'll ignore
     *      errors
     * @throws Exception
     */ 
    public void invoke( List mbeans, String operation, boolean failFirst )
            throws Exception;

    /** Register a bean by creating a modeler mbean and adding it to the 
     * MBeanServer.
     * 
     * If metadata is not loaded, we'll look up and read a file named
     * "mbeans-descriptors.ser" or "mbeans-descriptors.xml" in the same package
     * or parent.
     *
     * If the bean is an instance of DynamicMBean. it's metadata will be converted
     * to a model mbean and we'll wrap it - so modeler services will be supported
     *
     * If the metadata is still not found, introspection will be used to extract
     * it automatically. 
     * 
     * If an mbean is already registered under this name, it'll be first
     * unregistered.
     * 
     * If the component implements MBeanRegistration, the methods will be called.
     * If the method has a method "setRegistry" that takes a RegistryMBean as
     * parameter, it'll be called with the current registry.
     * 
     *
     * @param bean Object to be registered
     * @param oname Name used for registration
     * @param type The type of the mbean, as declared in mbeans-descriptors. If
     * null, the name of the class will be used. This can be used as a hint or
     * by subclasses.
     *
     * @since 1.1
     */ 
    public void registerComponent(Object bean, String oname, String type)
           throws Exception;

    /** Unregister a component. We'll first check if it is registered,
     * and mask all errors. This is mostly a helper.
     * 
     * @param oname
     * 
     * @since 1.1
     */ 
    public void unregisterComponent( String oname );


     /** Return an int ID for faster access. Will be used for notifications
      * and for other operations we want to optimize. 
      *
      * @param domain Namespace 
      * @param name  Type of the notification
      * @return  An unique id for the domain:name combination
      * @since 1.1
      */
    public int getId( String domain, String name);


    /** Reset all metadata cached by this registry. Should be called 
     * to support reloading. Existing mbeans will not be affected or modified.
     * 
     * It will be called automatically if the Registry is unregistered.
     * @since 1.1
     */ 
    public void stop();

    /** Load descriptors. The source can be a File, URL pointing to an
     * mbeans-descriptors.xml.
     * 
     * Also ( experimental for now ) a ClassLoader - in which case META-INF/ will
     * be used.
     * 
     * @param source
     */ 
    public void loadMetadata(Object source ) throws Exception;
}